U.S. patent application number 10/984405 was filed with the patent office on 2005-04-21 for information signal copy managing method, information signal recording method, information signal output apparatus, and recording medium.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Kori, Teruhiko, Otsuka, Masaya.
Application Number | 20050086488 10/984405 |
Document ID | / |
Family ID | 15574840 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050086488 |
Kind Code |
A1 |
Kori, Teruhiko ; et
al. |
April 21, 2005 |
Information signal copy managing method, information signal
recording method, information signal output apparatus, and
recording medium
Abstract
An information signal copy managing method for properly
protecting the copyright of information signals and, at the same
time, guaranteeing user advantages in copying information signals
within a limited range. Information indicative of the start and end
of each piece of information content covered by copyright is
superimposed thereon as electronic watermark information. The
resultant information signal is transmitted. When the received
information signal is copied, both the information indicative of
the start of the information content and the information indicative
of the end thereof are detected from the electronic watermark
information, determining the completion of copying. Thus, copying
of information content is managed.
Inventors: |
Kori, Teruhiko; (Kanagawa,
JP) ; Otsuka, Masaya; (Tokyo, JP) |
Correspondence
Address: |
FROMMER LAWRENCE & HAUG LLP
10TH FLOOR
745 FIFTH AVENUE
NEW YORK
NY
10151
US
|
Assignee: |
SONY CORPORATION
|
Family ID: |
15574840 |
Appl. No.: |
10/984405 |
Filed: |
November 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10984405 |
Nov 9, 2004 |
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09580141 |
May 30, 2000 |
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6836844 |
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Current U.S.
Class: |
713/176 ;
386/E5.004; G9B/20.002 |
Current CPC
Class: |
G11B 27/36 20130101;
H04N 2005/91335 20130101; G11B 27/034 20130101; H04N 5/913
20130101; G11B 20/00181 20130101; G11B 20/00884 20130101; H04N
21/42646 20130101; H04N 21/4627 20130101; G11B 2220/2545 20130101;
G11B 20/00224 20130101; G11B 20/00753 20130101; H04N 2005/9135
20130101; G11B 20/0021 20130101; G11B 2220/20 20130101; G11B
20/00086 20130101; H04N 21/4325 20130101; G11B 2220/2529 20130101;
H04N 21/8358 20130101; H04N 2005/91328 20130101; G11B 20/00514
20130101; G11B 20/00557 20130101; G11B 20/00768 20130101; H04N
21/8456 20130101 |
Class at
Publication: |
713/176 |
International
Class: |
H04L 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 1999 |
JP |
11-154005 |
Claims
1. An information signal copy managing method comprising the steps
of: superimposing information indicative of a start of and
information indicative of an end of a portion of each piece of
information content, said portion being covered by copyright, onto
said each piece of information content as electronic watermark
information to transmit a resultant information signal; and when
copying and recording said information signal, determining
completion of copying of said each piece of information content
when both of said information indicative of the start of and said
information indicative of the end of said copyrighted portion are
detected from said electronic watermark information, thereby
executing copy management.
2. The information signal copy managing method according to claim
1, wherein copy control information is further added to said each
piece of information content as electronic watermark information
and, when copying and recording said each piece of information
content, copying is controlled for said each piece of information
content on the basis of said copy control information detected from
said signal information.
3. The information signal copy managing method according to claim
1, wherein identification information of said each piece of
information content is further added to said information signal as
electronic watermark information and, when copying and recording
said each piece of information content, copying of said each piece
of information content is managed also by use of said
identification information detected from said information
signal.
4. An information signal copy managing method comprising the steps
of: attaching identification information for identifying each piece
of information content to the same and superimposing information
indicative of a start of and information indicative of an end of a
portion of said each piece of information content, said portion
being covered by copyright, onto said each piece of information
content to transmit a resultant information signal; and identifying
said each piece of information content to be copied and recorded by
said identification information for each recording apparatus and,
when both of said information indicative of the start of and said
information indicative of the end of said copyrighted portion are
detected from said electronic watermark information, updating copy
permitted count for said each piece of information content.
5. The information signal copy managing method according to claim
4, wherein said identification information is also superimposed on
said each piece of information content as electronic watermark
information.
6. The information signal copy managing method according to claim
4, wherein said recording apparatus manages copy count managing
information by storing the same in a memory thereof as copy history
information, said copy count managing information being for
managing a copy permitted count of said each piece of information
content identified by said identification information; and when
copying said each piece of information content, references said
copy history information about said each piece of information
content to be copied to control copying and, when both of said
information indicative of the start of and said information
indicative of the end of said copyrighted portion are determined
from said electronic watermark information, updates said copy
history information about said each piece of information
content.
7. (canceled)
8. (canceled)
9. The information signal copy managing method according to claim
4, wherein said information signal is further attached with copy
control information for said each piece of information content as
electronic watermark information.
10. The information signal copy managing method according to claim
1, wherein a unit of said each piece of information content
identified by said identification information is a piece of music
indicated by one title.
11. An information signal recording apparatus for recording an
information signal on a recording medium, comprising: a
superimposing means for superimposing, on each piece of information
content, information indicative of a start of and information
indicative of an end of a portion of said each piece of information
content, said portion being covered by copyright, as electronic
watermark information.
12. The information signal recording apparatus for recording an
information signal on a recording medium according to claim 11,
further comprising: an attaching means for attaching copy control
information to said each piece of information content as electronic
watermark information.
13. The information signal recording apparatus for recording an
information signal on a recording medium according to claim 11,
further comprising: an attaching means for attaching identification
information for identifying said each piece of information content
to the same as electronic watermark information.
14. The information signal recording apparatus for recording an
information signal on a recording medium according to claim 11,
further comprising: an attaching means for attaching information
about copy permitted count for said each piece of information
content to the same as electronic watermark information.
15. The information signal recording apparatus for recording an
information signal on a recording medium according to claim 11,
wherein a unit of said each piece of information content identified
by said identification information is a piece of music indicated by
one title.
16. An information signal output apparatus for outputting an
information signal, comprising: a superimposing means for
superimposing, on each piece of information content, information
indicative of a start of and information indicative of an end of a
portion of said each piece of information content, said portion
being covered by copyright, as electronic watermark
information.
17. The information signal output apparatus for outputting an
information signal according to claim 16, further comprising: an
attaching means for attaching copy control information to said each
piece of information content as electronic watermark
information.
18. The information signal output apparatus for outputting an
information signal according to claim 16, further comprising: an
attaching means for attaching identification information for
identifying said each piece of information content to the same as
electronic watermark information.
19. The information signal output apparatus according to claim 16,
further comprising: an attaching means for attaching information
about copy permitted count for said each piece of information
content to the same.
20. The information signal output apparatus for outputting an
information signal according to claim 16, wherein a unit of said
each piece of information content identified by said identification
information is a piece of music indicated by one title.
21. An information signal recording apparatus for copying and
recording an information signal in which information indicative of
a start of and information indicative of an end of a portion of
each piece of information content, said portion being covered by
copyright, are superimposed on said each piece of information
content as electronic watermark information, said information
signal recording apparatus comprising: an electronic watermark
information detecting means for detecting said electronic watermark
information from said each piece of information content to be
copied and recorded; and a copy completion post-processing means
for executing post-processing as completion of copying of said each
piece of information content when both of said information
indicative of the start of and said information indicative of the
end of said copyrighted portion are detected by said electronic
watermark information detecting means.
22. The information signal recording apparatus according to claim
21, wherein said information signal is further attached with copy
control information as electronic watermark information for said
each piece of information content; and said information signal
recording apparatus further comprising a copy control means for
executing copy control on said each piece of information content on
the basis of said copy control information detected from said
information signal at the time of copying and recording of said
each piece of information content.
23. An information signal recording apparatus for copying and
recording an information signal in which identification information
for identifying each piece of information content is attached to
the same and information indicative of a start of and information
indicative of an end of a portion of said each piece of information
content, said portion being covered by copyright, are superimposed
on said each piece of information content as electronic watermark
information, said information signal recording apparatus
comprising: an identification information detecting means for
detecting said identification information from said each piece of
information content to be copied and recorded; a memory for storing
and managing, as copy history information, copy count managing
information for managing copy permitted count for said each piece
of information content identified by said identification
information detected by said identification information detecting
means; a copy control means for executing copying and recording
control on the basis of said copy history information stored in
said memory about said each piece of information content identified
by said identification information detected by said identification
information detecting means when copying and recording said each
piece of information content; an electronic watermark information
detecting means for detecting said electronic watermark information
from said each piece of information content to be copied and
recorded; and a copy history updating means for updating said copy
history information about said each piece of information content
when both of said information indicative of the start of and said
information indicative of the end of said copyrighted portion are
detected by said electronic watermark information detecting means
if copying and recording are executed by said copy control
means.
24. The information signal recording apparatus according to claim
23, wherein said information signal is further attached with copy
control information for said each piece of information content as
electronic watermark information; and said copy control means also
executes copy control on said each piece of information content on
the basis of said copy control information detected from said
information signal at copying and recording said each piece of
information content.
25. (canceled)
26. The information signal recording apparatus according to claim
23, wherein a unit of said each piece of information content
identified by said identification information is a piece of music
indicated by one title.
27. An information signal copy managing method for managing copying
comprising the steps of: superimposing identification information
for each piece of information content as electronic watermark
information onto at least an entire section of said each piece of
information content, said entire section being covered by copyright
and transmitting a resultant information signal; detecting a change
point in said identification information of said electronic
watermark information as a copy start position and a copy end
position of said each piece of information content at copying and
recording of said information signal; and determining completion of
copying of said each piece of information content when both of said
copy start position and said copy end position are detected.
28. The information signal copy managing method according to claim
27, wherein said information signal is further attached with copy
control information as electronic watermark information for said
each piece of information content and copy control is executed on
said each piece of information content on the basis of said copy
control information detected from said information signal at
copying and recording of said each piece of information
content.
29. The information signal copy managing method according to claim
27, wherein copy management is executed on said each piece of
information content also by use of said identification information
detected from said information signal at copying and recording of
said each piece of information content.
30. The information signal copy managing method comprising the
steps of: superimposing identification information for each piece
of information content as electronic watermark information onto at
least an entire section of said each piece of information content,
said entire section being covered by copyright and transmitting a
resultant information signal; identifying, by said identification
information, for each recording apparatus, said each piece of
information content to be copied and recorded and, at the same
time, detecting a change point in said identification information
as a copy start position and a copy end position of said each piece
of information content; and when both of said copy start position
and said copy end position are detected, updating a copy permitted
count for said each piece of information content.
31. The information signal copy managing method according to claim
30, wherein said recording apparatus storing for management, in a
memory of said recording apparatus, as copy history information,
copy count managing information for managing said copy permitted
count for said each piece of information content identified by said
identification information; and when copying said each piece of
information content, referencing said copy history information
about said each piece of information content to be copied to
control copying and, when both of said copy start position and said
copy end position are detected, updating said copy history
information about said each piece of information content.
32. (canceled)
33. (canceled)
34. The information signal copy managing method according to claim
30, wherein said information signal is further attached with copy
control information for each piece of said information content as
electronic watermark information.
35. The information signal copy managing method according to claim
27, wherein a unit of said information content identified by said
identification information is a piece of music indicated by one
title.
36. A recording medium recorded with an information signal in which
information indicative of a start of and information indicative of
an end of a portion of each piece of information content, said
portion being covered by copyright, are superimposed on said each
piece of information content as electronic watermark
information.
37. The recording medium according to claim 36, wherein said
information signal is further attached with copy control
information for said each piece of information content as
electronic watermark information.
38. The recording medium according to claim 36, wherein said
information signal is still further attached with identification
information for identifying said each piece of information content
as electronic watermark information.
39. The recording medium according to claim 38, wherein said
information signal is yet further attached with a copy permitted
count for said each piece of information content as electronic
watermark information.
40. A recording medium recorded with an information signal in which
identification information for identifying each piece of
information content is superimposed, as electronic watermark
information, at least on an entire section of said each piece of
information content, said entire section being covered by
copyright.
41. The recording medium according to claim 40, wherein said
information signal is further attached with copy control
information for said each piece of information content as
electronic watermark information.
42. The recording medium according to claim 41, wherein said
information signal is still further attached with a copy permitted
count for said each piece of information content as electronic
watermark information.
43. The information signal copy managing method according to claim
4, wherein a unit of said each piece of information content
identified by said identification information is a piece of music
indicated by one title.
44. The information signal copy managing method according to claim
30, wherein a unit of said information content identified by said
identification information is a piece of music indicated by one
title.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to a information
signal copy managing method for managing copying of various
information contents such as an audio signal and a video signal for
example, an information signal output apparatus and an information
signal recording apparatus that operate on the basis of this
method, and a recording medium for recording information
signals.
[0002] Recent widespread proliferation of digital content provided
by the Internet, a compact disc (CD), and a digital video disc
(DVD) for example poses a new problem of the copyright infringement
by the unauthorized copy (duplication) of digital content. To
prevent the unauthorized copy, a method has been proposed in which
additional information for copy control is attached to digital
content.
[0003] The prevention of copying is controlled in two manners
according to information sources; no copy is allowed at all and
copy is allowed only once and therefore a copy cannot be further
duplicated (copy control with limited copy generation). The former
is applied the original software which is created and sold by
content makers as with DVD-ROMs for example. The latter is applied
to the information which is broadcast in broadcast media for
example.
[0004] The copy control with limited copy generation requires
schemes for effectively controlling copy generation. The schemes
include SCMS (Serial Copy Management System) and CGMS (Copy
Generation Management System) for example.
[0005] In SCMS, digital copy is permitted only once by use of a
copy enable/disable flag and a category code indicative of a
digital audio system type such as CD (Compact Disc) or DAT (Digital
Audio Tape) for example, these flag and category code being
transmitted with a digital audio signal.
[0006] Namely, SCMS information consisting of the copy
enable/disable flag and the category code to be transmitted with a
digital audio signal allows copy of the digital audio signal of the
first generation but does now allow copying of the duplicated
digital audio signal.
[0007] In CGMS, in the case of an analog image signal for example,
2-bit additional information for copy control is superimposed on a
particular horizontal interval in the signal's vertical blanking
period and, in the case of a digital image signal, this additional
information is added to digital image data for transmission.
[0008] The 2-bit additional information (hereafter referred to as
CGMS information) conveys the following means:
[0009] "00" . . . copy permitted;
[0010] "10" . . . copy permitted only once (only for one
generation); and
[0011] "11" . . . copy prohibited.
[0012] If the CGMS information attached to image information is
"10", a CGMS-compliant recording apparatus determines that the
image information can be duplicated and executes a recording (or
duplicating) operation. As a result, CGMS information "11" is added
to the recorded image information. When the CGMS information thus
attached to image information to be recorded is "11", the
CGMS-compliant apparatus determines that this image signal cannot
be copied, disabling further recording processing.
[0013] Thus, SCMS and CGMS control the copy generation of audio
signals and video signals (or image information).
[0014] Use of above-mentioned SCMS or CGMS can prevent a copied
information signal from being copied onto another recording medium.
However, there is still a problem that a first-generation
information signal provided by a content maker in the form of a CD
for example can be infinitely duplicated from that CD by use of the
same recording apparatus.
[0015] Consequently, instead of the above-mentioned copy generation
control schemes which pose a danger of unauthorized mass copy, a
scheme may be proposed in which information signals are provided in
the form of copy-prohibited discs for example, thereby disabling
copying of information signals from the beginning.
[0016] This scheme can securely protect the copyright of
information signals. However, this scheme allows users to use
information signals only from the copy-inhibited disc, thereby
significantly limiting user advantages in the use of information
signals.
[0017] For example, the copy-prohibited disc limits the usage of
information signals in which the user selects desired titles of
music from the disc and duplicates the selected titles onto a
small-sized magneto-optical disc called an MD (Mini Disc) or a
cassette tape for reproduction on a car stereo device or a portable
player for personal enjoyment.
[0018] To overcome this problem, a method has been proposed in
which the copyright of information signals can be properly
protected and, at the same time, user convenience for using
information signals by duplicating them within a limited range can
be ensured. To be specific, this method limits the number of times
copy can be made in which each recording apparatus controls the
number times copy is made for each piece of information content
("information content" herein denotes each music or movie title for
example), one title being copied only by the predetermined number
of times.
[0019] However, if this proposed method decrements the number of
times copy can be made when the stop key of a recording apparatus
is inadvertently pressed during recording of a title for example,
it counts up for an incomplete copy, putting the user at a great
disadvantage.
SUMMARY OF THE INVENTION
[0020] It is therefore an object of the present invention to
provide an information signal copy managing apparatus, an
information signal recording apparatus, an information signal
output apparatus, and a recording medium that overcome the
above-mentioned problems by allowing the user to fully understand
the completion of copy and recording of each piece of information
content.
[0021] In carrying out the invention and according to one aspect
thereof, there is provided an information signal copy managing
method comprising the steps of: superimposing information
indicative of a start of and information indicative of an end of a
portion of each piece of information content, the portion being
covered by copyright, onto each piece of information content as
electronic watermark information to transmit a resultant
information signal; and, when copying and recording the information
signal, determining completion of copying of each piece of
information content when both of the information indicative of the
start of and the information indicative of the end of that portion
are detected from the electronic watermark information, thereby
executing copy management.
[0022] Detection of the information indicative of the start of and
the information indicative of the end of the copyrighted portion as
electronic watermark information is determined as the completion of
copying of the information content. Consequently, a copy operation
that failed due to an erroneous user operation for example is not
recognized as complete, thereby guaranteeing user advantages in
copying information signals within a limited range.
[0023] In addition, start position information and end position
information are superimposed on the information content as
electronic watermark information. This makes it difficult to tamper
the start and end position information, thereby properly protecting
the copyright of the provided information content.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] These and other objects of the invention will be seen by
reference to the description, taken in connection with the
accompanying drawing, in which:
[0025] FIG. 1 is a block diagram illustrating a configuration of an
information signal recording apparatus practiced as one preferred
embodiment of the invention;
[0026] FIG. 2 is a diagram illustrating one example of electronic
watermark information for use in an information signal copy
managing method according to the invention;
[0027] FIG. 3 is a block diagram illustrating an electronic
watermark superimposing method for use in the above-mentioned
embodiment;
[0028] FIG. 4 is a diagram illustrating a state in which electronic
watermark is superimposed on information content in the
above-mentioned embodiment;
[0029] FIG. 5 is a block diagram illustrating one example of an
information signal reproducing apparatus;
[0030] FIG. 6 is a block diagram illustrating one example of an
information signal recording apparatus practiced as one preferred
embodiment of the invention;
[0031] FIG. 7 is a diagram illustrating contents of a copy history
management memory provided in the embodiment of the information
signal recording apparatus of the invention;
[0032] FIG. 8 is a flowchart for describing copy control processing
in the embodiment of the information signal recording
apparatus;
[0033] FIG. 9 is a diagram illustrating another example of the
electronic watermark information superimposing method according to
the invention;
[0034] FIG. 10 is a block diagram illustrating the electronic
watermark superimposing method shown in FIG. 9; and
[0035] FIG. 11 is a flowchart for describing another example of
copy control processing in the embodiment of the information signal
recording apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] This invention will be described in further detail by way of
preferred embodiments of an information signal copy managing
method, an information signal output apparatus, an information
signal recording apparatus, and a recording medium with reference
to the accompanying drawings.
[0037] In the following embodiments, an example is used for
description in which audio signals representing music for example
are provided in the form of a compact disc (hereafter referred to
as a CD) as content information, the audio signals recorded on this
CD are reproduced by a CD player to be copied by a recording
apparatus onto a mini disc (hereafter referred to as an MD).
[0038] About an Authoring Apparatus:
[0039] FIG. 1 illustrates a configuration of an audio signal
recording apparatus for making a master CD on which music (an audio
signal) is recorded as an example of information content. This
recording apparatus is used on the content maker side and is
generally called an authoring apparatus.
[0040] As shown in FIG. 1, the authoring apparatus of this
embodiment comprises an input terminal 1, an electronic watermark
information superimposing block (hereafter referred to as an WM
superimposing block) 2, an electronic watermark information forming
block (hereafter referred to as a WM forming block) 3, a content ID
generating block 4, a copy control information generating block 5,
an A/D converter 6, a recording encoding block 7, an additional
information attaching block 8, a writing block 9, a controller 10,
and a key operating block 11. A CD 100 is a CD on which music is
recorded by this authoring apparatus of this embodiment.
[0041] In the authoring apparatus of this embodiment, music as
information content is recorded on the CD 100 with content ID and
copy control information attached as additional electronic
watermark information. Therefore, these pieces of additional
information are generated by the content ID generating block 4 and
the copy control information generating block 5 shown in FIG.
1.
[0042] The content ID generating block 4 generates a content ID as
identification information for identifying each piece of
information content to be recorded on the CD 100. In the present
embodiment, ISRC (International Standard Recording Code) is used
for the content ID.
[0043] This ISRC consists of 12 characters such as
"SE-T38-86-302-12" for example as shown in FIG. 2. To reduce the
data quantity, the ISRC may be coded for data compression. The ISRC
in this example is 8-byte information for example after data
compression.
[0044] The copy control information generating block 5 comprises a
copy generation managing information generating block 51, a copy
count managing information generating block 52, and a start/end
flag generating block 53.
[0045] In the present embodiment, 2-bit CGMS information is used
for the copy generation managing information generated by the copy
generation managing information generating block 51. For the copy
count managing information, the information about the copy
permitted count for each piece of information content determined by
copyright holder is used. This copy permitted count information is
3 bits wide in this example, specifying the number of times copy is
permitted; zero time (copy prohibited), once, twice, . . . ,
infinite (copy free).
[0046] The start/end flag generating block 53 generates a start
flag and an end flag indicative of the start and end of a portion
covered by copyright. These start flag and end flag are each 1-bit
information.
[0047] In the present embodiment, these start flag and end flag are
adapted to set up (for example, become "1") at the start and end of
each piece of information content.
[0048] Because these start and end flags are for detection of the
completion of copy, they may be adapted so that they indicate the
start and end of a portion that includes most information content.
Namely, the start and end flags need not be set up by exactly
matching the start and end of each piece of information
content.
[0049] Meanwhile, a copyright holder may want to regard the copy of
the first chorus, which is most popular, of a piece of music as the
complete copy of it. In consideration thereof, if a piece of music
consists of 3 choruses, the end flag may be set up for each of
these choruses. In this case, if plural pieces of information
content identified by the same ISRC end in 1 chorus, the copy may
be regarded as complete. When 3 choruses have all been copied,
plural end flags are detected. Superimposition of the same ISRC on
the information content from its start to its end and combination
thereof beforehand provides 1 copy.
[0050] Namely, the positions at which the start and end flags are
set up may be any positions that can be compromised between
copyright holder and user as the start and end of plural portions
completion and detection of information content.
[0051] In the present embodiment, copy control information is made
up of 8-bit (1-byte) information B0 through B7 as shown in FIG. 2.
Thus, assignment of start flag, end flag, CGMS information, and
copy permitted count as copy control information as 1 word allows
detection of these pieces of information at a time.
[0052] Referring to FIG. 2, CGMS (1) and CGMS (2) indicate first
bit 1 and second bit respectively of CGMS information. Copy number
(1), copy number (2), and copy number (3) indicate first bit,
second bit, and third bit respectively of copy permitted count.
"Reserved" denotes a reserve bit.
[0053] Before starting recording music on the CD 100, the operator
of the authoring apparatus of the present embodiment inputs the
content ID, CGMS information, copy permitted count, and start/end
flag insertion interval (an interval in which the start and end
flags are set to "1") into the authoring apparatus through the key
operating block 11. On the basis of the inputs made by the
operator, the controller 10 generates and supplies a control signal
directing what kind of information to be generated to the content
ID generating block 4 and the copy control information generating
block 5. Normally, the start flag/end flag insertion interval is an
interval from the start of information content to a predetermined
time and an interval from the end of information content to a
predetermined time.
[0054] On the basis of the control signal supplied from the copy
control information generating block 5, the content ID generating
block 4 and the copy control information generating block 5 form
the content ID and the copy control information respectively
according to the inputs specified by the user of the authoring
apparatus and supply these pieces of information to the WM forming
block 3 and the additional information attaching block 8.
[0055] The WM forming block 6 execute electronic watermark
processing on both the supplied content ID and copy control
information, forming the electronic watermark information for them.
As described, electronic watermark processing is executed to embed
information as noise into the portions of image data or music data
which are not essential for human perception, namely the portions
which are not redundant to music or image.
[0056] Referring to FIG. 3, there is shown one example of the WM
forming block 6 of the present embodiment. In this example,
spectrum spread processing is used for electronic watermark
processing. Specifically, the content ID and the copy control
information are spectrum-spread by PN (Pseudorandom Noise) codes of
different systems to form the electronic watermark information.
[0057] Namely, in the WM forming block 6 shown in FIG. 3, the ISRC
supplied from the content ID generating block 4 is supplied to the
spreading block 301 to be multiplied by a PN code PNa of one series
supplied from a PNa generating block 303, providing a spread
spectrum signal. This spread spectrum signal is then supplied to a
mixing block 305.
[0058] On the other hand, the copy control information supplied
from the copy control information generating block 5 is supplied to
a spreading block 302 to be multiplied by a PN code PNb of a
different series, providing a spread spectrum signal. This spread
spectrum signal is then supplied to the mixing block 305.
[0059] The spread spectrum signals of two systems are mixed in the
mixing block 305 to be supplied to the WM superimposing block
2.
[0060] A signal Au (an analog audio signal) of a piece of music to
be recorded on the CD 100 is supplied to the WM superimposing block
2 through the input terminal 1. As described, the WM superimposing
block 2 superimposes the electronic watermark information
consisting of the spread spectrum signal of the content ID formed
by the WM forming block 6 and the spread spectrum signal of the
copy control signal onto the analog audio signal Au supplied
through the input terminal 1. In this case, the superimposition is
performed at a level which is low enough for the watermark to be
inconspicuous as noise for the audio signal Au. Alternatively, the
superimposition is performed at a relatively high level in portions
where noise is inconspicuous and at a relatively low level in other
portions by use of human auditory characteristics.
[0061] In this example, the electronic watermark information of
content ID and the electronic watermark information of copy control
information are superimposed on the entire interval from the start
to the end of each piece of information content as shown in FIG.
4.
[0062] It should be noted that the bit of the start flag of the
copy control information is "1" at the beginning of the information
content indicated as "START" shown in FIG. 4. At the end of the
information content indicated as "END" shown in FIG. 4, the bit of
the end flag of the copy control information is "1". In the portion
of the information content between "START" and "END", the bits of
the start and end flags of the copy control information are both
"0"s.
[0063] It should also be noted that the electronic watermark
information of content ID and the electronic watermark information
are superimposed on the entire interval between the start and end
of each piece of information content, resulting in a state in which
each electronic watermark information is superimposed repeatedly
multiple times.
[0064] The audio signal superimposed with the content ID and the
copy control information as electronic watermark information in the
WM superimposing block 2 is supplied to the A/D converter 6 to be
converted into a digital signal, which is supplied to the recording
encoding block 7.
[0065] The recording encoding block 7 compresses the supplied
digital audio signal by a predetermined scheme and executes error
correction encoding on the digital audio signal. The resultant
signal is outputted to the additional information attaching block
8. The additional information attaching block 8 attaches the
above-mentioned content ID supplied from the content ID generating
block 4 and the copy control information supplied from the copy
control information generating block 5 to the compressed digital
audio data.
[0066] This additional information attaching block 8 attaches the
information for controlling copying of the compressed digital audio
data. In the present embodiment, the copy control information
includes the start and end flags, so that the completion of copy of
the digital compressed data may also be properly understood by use
of these start and end flags.
[0067] In this example, the compressed digital audio data are made
up of blocks having a predetermined size. The content ID and the
copy control information are attached to each block of data.
However, because the content ID has a comparatively large data
size, it may be attached over two or more blocks.
[0068] Then, the digital audio signal supplied from the additional
information attaching block 8 is recorded on the CD 100 through the
writing block 9.
[0069] Thus, the CD 100 is created in which the copy control
information composed of start and end flags, CGMS information, and
copy permitted count, and the content ID are superimposed as
electronic watermark information respectively and the information
content attached as digital additional information is recorded. In
the present embodiment, many CDs recorded with the same information
are copied from this CD 100 (namely, the master CD) for
distribution to many end users.
[0070] Reproducing Apparatus:
[0071] Referring to FIG. 5, there is shown a diagram illustrating a
reproducing apparatus for reproducing the audio signal according to
the invention. In the present embodiment, the audio signal
reproducing apparatus shown in FIG. 5 is a CD player. The CD player
of the present embodiment can reproduce a CD 100S created on the
basis of the CD 100 created by the authoring apparatus shown in
FIG. 1.
[0072] As shown in FIG. 5, the CD player of the present embodiment
comprises a reading block 21, a data decoding block 22, a D/A
converter 23, an analog audio signal output terminal 23a, a digital
interface 24, and a digital audio signal output terminal 24d.
[0073] The reading block 21 reads the digital audio signal of the
information content recorded on the CD 100S. The read digital audio
signal is supplied to the data decoding block 22 and the digital
interface 24.
[0074] The data decoding block 22 decodes the information content
of music, which is the digital audio signal compressed by the
predetermined scheme, and supplies the decompressed digital signal
to the D/A converter 23. The D/A converter 23 converts the digital
audio signal into an analog audio signal and outputs the analog
audio signal, which is the information content of music, through
the output terminal 23a.
[0075] In the example, the content ID and the copy control
information attached to the digital audio signal in the additional
information attaching block 8 of the above-mentioned authoring
apparatus are lost in the course of decoding the digital audio
signal and converting it into the analog audio signal.
[0076] However, the content ID and the copy control information of
the electronic watermark information superimposed on the same time
domain as that of the analog audio signal are not lost but
outputted along with the analog audio signal to a speaker, an
earphone, a headphone, or an audio signal recording apparatus, not
shown.
[0077] On the other hand, the compressed digital audio signal with
the content ID and the copy control information attached is
supplied to the digital interface 24. This compressed digital audio
signal is outputted through the output terminal 24d. For the
digital interface in this example, the IEEE 1394 serial bus
interface using CGMS information and having encrypted copyright
protection is used for example.
[0078] To be more specific, the output of the digital audio
information is transmitted, in the compressed state, by the IEEE
1394 interface between the units compliant thereto. The
transmission digital information is encrypted in the IEEE 1394
interface to prevent unauthorized copy. This interface also
determines whether the transmission digital signal is sent to a
unit compliant with the IEEE 1394 bus interface (hereafter, this
unit is referred to as a compliant unit) or the recording
apparatus. At the same time, this interface verifies the CGMS
information, which is the information for copy control. According
to the result of this verification, this interface determines
whether to send a key for decrypting the encrypted copyright
protection to the destination unit.
[0079] Namely, the compressed digital audio signal is encrypted by
an encryption key which is different for every transmission and the
encrypted signal is outputted. In doing so, communication is made
with the destination unit through the digital interface 24 to
determine whether the destination unit is a compliant unit. If the
destination unit is found a compliant unit, it is determined
whether this destination unit is a recording apparatus or not.
[0080] Then, according to the decision of the CGMS information
attached to the digital audio signal and the decision for the
destination unit made through the digital interface 24, it is
determined whether to send cipher key information for decrypting
the encryption.
[0081] For example, if the destination unit is a noncompliant unit,
the cipher key information is not passed to the destination unit.
Even if the destination unit is a compliant unit, the cipher key
information is not passed thereto if it is a recording apparatus
and the CGMS information is "11".
[0082] The above-mentioned communication control scheme effectively
prevents the unauthorized copy of audio digital data.
[0083] Recording Unit:
[0084] Referring to FIG. 6, there is shown a preferred embodiment
of the audio signal recording apparatus that receives the signals
of the information content in the form of an analog audio signal
reproduced by the CD player shown in FIG. 5 and the information
content in the form of a digital compressed signal and records
these signals on a recording medium. This recording apparatus is
the recording system of a recording/reproducing apparatus
(hereafter referred to as an MD apparatus) that uses an MD (Mini
Disc) for the recording medium. In FIG. 6, the reproducing system
of the MD apparatus is omitted for the simplicity of
description.
[0085] The MD recording apparatus comprises an analog interface and
a digital interface, receives information contents in the forms of
analog audio signal and a digital audio signal, and executes copy
control on the basis of the copy count for that information content
in the MD recording apparatus. If copy is permitted, the MD
recording apparatus duplicates the information content on an MD
200, confirms the completion of copying, and decrements the copy
permitted count by one in the MD recording apparatus.
[0086] For this copy count control, the MD recording apparatus has
a copy history information managing memory 41. This memory stores,
as copy history information, a table TB listing the correlation
between content ID and copy permitted count of the information
content identified by that ID in this MD recording apparatus as
shown in FIG. 7.
[0087] If the MD recording apparatus determines that certain
information content is first one that has been entered in the MD
recording apparatus, the content ID and copy permitted count in the
copy control information attached to that information content are
entered in the copy history information table TB as the history
information about that information content. Then, the MD recording
apparatus duplicates the inputted information content and, upon
confirmation of the completion of copying, decrements the copy
permitted count by one for the copied information content.
[0088] When that information content is inputted in the MD
recording apparatus again, the content ID attached to that
information content and the copy permitted count in the copy
control information are not entered in the table TB because that
information content is already stored in the table TB. Then, from
the copy permitted count for the information content indicated by
the content ID in the table TB, the MD recording apparatus
determines whether that information content can be copied in the MD
recording apparatus. If the information content is found
duplicatable, the MD recording apparatus decrements the copy
permitted count in the table TB by one upon completion of
copying.
[0089] Thus, the MD recording apparatus controls the copy permitted
count for each piece of information content as limited. It should
be noted that, in this embodiment, copy generation control is also
executed on the basis of CGMS information.
[0090] Copy Control of Information Content in the MD Recording
Apparatus:
[0091] Information content of music inputted through an analog
input terminal 31a is supplied to an A/D converter 33 through an
analog interface 32 to be converted into a digital signal. The
digital signal is supplied to an encoding block 34. In the encoding
block 34, predetermined data compression processing and error
correction encoding processing are executed on the digital signal.
The resultant digital signal is supplied to a selector 38.
[0092] The analog audio signal from the analog interface 32 is
supplied to an electronic watermark detecting block (hereafter
referred to as a WM detecting block) 35. The WM detecting block 35
despreads the analog audio signal by use of the PN code sequences
PNa and PNb used in the WM forming block 3 shown in FIG. 3,
detecting the content ID and the copy control information
superimposed as electronic watermark information. The detected
content ID and copy control information are supplied to a
controller 40.
[0093] In this case, the copy control information is 8 bits wide
and therefore detected comparatively more easily than the content
ID. Therefore, the start and end flags can be confirmed
quickly.
[0094] The controller 40 identifies the information content
inputted as an analog audio signal from the input terminal 31a by
the content ID supplied from the WM detecting block 35 and, on the
basis of the copy control information, determines whether to
duplicate the information content. If the information content is to
be copied, the control block 40 checks both the start and end
flags, confirming the completion of copying. Then, the control
block 40 decrements the copy permitted count for the information
content in the copy history information managing memory 41 by one,
updating the copy history information.
[0095] A digital audio signal coming from a digital audio signal
input terminal 31d through a digital interface 36 is supplied to an
additional information extracting block 37. The additional
information extracting block 37 extracts the content ID and copy
control information from the compressed digital data, supplying the
extracted content ID and copy control information to the selector
38.
[0096] The control block 40 identifies the information content
inputted as a compressed digital audio signal from the input
terminal 31d by use of the content ID supplied from the additional
information extracting block 35 and, on the basis of the copy
control information, determines whether to duplicate the
information content. If the information content is to be copied,
the controller 40 checks both the start and end flags, confirming
the completion of copying. Then, the controller 40 decrements the
copy permitted count for the information content in the copy
history information managing memory 41 by one, updating the copy
history information.
[0097] On the basis of a selector control signal corresponding to
the input made by the user from a key operating block 39, the
selector 38 selects one of the data supplied from the encoding
block 34 and the data supplied from the digital interface block 36
and outputs the selected data to a recording control block 43
through the additional information attaching block 42.
[0098] The copy control information to be attached to the copied
digital audio data is supplied along with the content ID from the
controller 40 to the additional information attaching block 42. For
example, if the CGMS information attached to the inputted
information content is "10" denoting the permission of copy once
and the inputted information content is to be copied, the CGMS
information is changed to "11" denoting the prohibition of copy and
the changed CGMS information is supplied from the controller 40 to
the additional information attaching block 42 as the copy control
information.
[0099] When the information content is to be performed, the
recording control block 43, under the control of the controller 40,
records the digital data on the MD 200; if copying is prohibited,
the recording control block 43 stops supplying the digital data to
the writing block 44, disabling the recording.
[0100] As described and will be described, the controller 40
references the CGMS information attached to the information content
or the copy history information to determine whether to duplicate
the information content for recording. The controller 40 sends a
control signal indicative of the decision to the recording control
block 43 to make the same execute the above-mentioned recording
control operation.
[0101] For example, if the copy history information in the copy
history information managing memory 41 for the information content
to be copied indicates copy permitted count=0, the controller 40
determines that the information content has been copied the
permitted number of times and therefore controls the recording
control block 42 not to duplicate the information content.
[0102] If the copy history information in the copy history
information managing memory 41 for the information content to be
duplicated indicates copy permitted count=1 or more, the controller
40 permits copying the information content. When copying has been
completed, the controller 40 decrements the copy permitted count of
the copy history information by one, updating the copy permitted
count of the copy history information stored in the copy history
information managing memory 41.
[0103] The following further describes the copy control processing
on the analog audio signal input in the MD recording apparatus
shown in FIG. 6 with reference to the flowchart shown in FIG. 8.
The processing shown in FIG. 6 is mainly executed by the controller
40.
[0104] First, the controller 40 determines whether the electronic
watermark information of content ID and the electronic watermark
information of copy control information are superimposed on the
information content in the state of an analog audio signal (step
S1). If the electronic watermark information is found not
superimposed, the controller 40 determines that this information
content is copy-free content and executes copying and recording
(step S11).
[0105] If the electronic watermark information is found
superimposed on the information content, the controller 40
references the CGMS information in the electronic watermark
information detected in the WM detecting block 35 (step S2). If
this CGMS information is found "11" indicating that copying is
prohibited, the controller 40 controls the recording control block
43 to disable the recording (step S8).
[0106] If the CGMS information is "00" or "10" indicating that
copying is permitted, the controller 40 starts a recording
operation (step S3). Then, the controller 40 detects the start flag
included in the electronic watermark information of the information
content, thereby detecting the beginning of the information content
(step S4). At the detection of the start flag, the controller 40
starts a preparing operation for storing the copy history in the
copy history information managing memory 41.
[0107] Then, the controller 40 detects and analyzes ISRC to
identify the information content (step S5). When the ISRC of the
information content is detected, the controller 40 searches the
copy history information managing memory 41 on the basis of this
ISRC to determine whether the copy history of this information
content is stored in the table TB in the memory 41 (step S6).
[0108] If the past history is found in the table TB, the controller
40 checks the copy permitted count for this information content
(step S7). If the copy permitted count is 0, the controller 40
stops recording (step S8). If the copy permitted count is 1 or
more, the controller 40 continues recording and determines whether
the end flag of the copy control information added to the
information content is set up or not (step S9). Then, the
controller 40 detects the end of the information content with the
end flag set up. When copying ends by the key operation by the
user, the controller 40 decrements the copy permitted count of the
copied information content by one, updating the copy history
information (step S10).
[0109] If the last history is not found in the table TB in step S6,
the controller 40 sets the content ID namely ISRC in the copy
control information attached to the information content and the
copy permitted count to the table TB as a preparatory operation for
storing the copy history in the copy history information managing
memory 41 as information content entered in the recording apparatus
for the first time. The controller 40 then detects the end of the
information content with the end flag set up (step S9). When
copying ends by the key operation by the user, the controller 40
decrements the copy permitted count of the copied information
content by one and rewrites the copy permitted count accordingly in
the table TB in the copy history information managing memory 41
(step S10).
[0110] As seen from the flowchart shown in FIG. 8, if the recording
is stopped by the user before the detection of the end flag or the
recording apparatus stops because the disc 200 is full, the
controller 40 determines copy is incomplete, not updating the table
TB in the copy history information managing memory 41.
Consequently, the incomplete copy of the recording information can
be made invalid.
[0111] If the information content is in the state of an analog
signal, the start and end flags are embedded as electronic
watermark information, so that the controller 40 can correctly
detect the start and end of the copyrighted portion of the
information content.
[0112] If an attempt for unauthorized copy makes tampering that one
or both of the start and end flags is removed from the information
content in order that the completion of copy is not detected, the
tampering is very difficult to practice because the start and end
flags are embedded in the same time domain and frequency area as
the information content as the electronic watermark information.
Thus, copy control management can be executed in the assured
manner.
[0113] For the detection of the beginning and end of information
content, it is possible to embed information indicative of elapsed
time such as a time code as the electronic watermark information in
the information content. However, this raises the data rate of the
additional information, making it difficult to embed the time code
without affecting the information content. If the time code can be
embedded anyhow, its detection becomes difficult.
[0114] On the contrary, the scheme of the above-mentioned
embodiment in which the start and end flags are embedded as
electronic watermark information requires less data quantity, is
easy in embedding the start and end flags as electronic watermark
information, and can detect them quickly.
[0115] It is also possible, for the detection of the beginning and
end of information content, to embed electronic watermark
information in the soundless interval between pieces of information
content (for example, between pieces of music) or in the black
screen between scenes. However, the electronic watermark
information embedded in the no-signal portion is prone to be
detected as noise and easy to be removed by an attempt for
unauthorized copy.
[0116] With the above-mentioned embodiment, the start and end flags
are embedded in the information content portion as electronic
watermark information, the above-mentioned problems are
circumvented.
[0117] In the above-mentioned example, the electronic watermark
information of content ID and the electronic watermark information
of copy control information are superimposed on the analog
information content. Alternatively, the electronic watermark
information may be superimposed on the baseband digital signal
before being compressed, which is the output of the A/D converter
6. In this case, even after the conversion of the digital
information content into an analog signal, the electronic watermark
information of copy control information can still be detected from
this analog information content.
[0118] It is also practicable to change the length of the copy
control information to 6 bits, separating the 2 bits of the start
and end flags. In this case, the 2-bit information is
spectrum-spread by PN code PNc of another PN code series to be
superimposed on the audio signal, thereby making it easier to
detect the start and end flags. Namely, in this case, the 2 bits of
the start and end flags may only be superimposed on the portion
indicated by "START" and "END" shown in FIG. 4 and only the start
flag bit is set to "1" in the "START" portion and only the end flag
bit is set to "1" in the "END" portion.
[0119] In the above-mentioned example, the electronic watermark
information is not embedded in the compressed digital data because
ISRC information and copy control information are added in separate
time domains. It is also practicable to embed the electronic
watermark information of content ID and copy control information
into the compressed digital data. For example, in the case of
compression by means of DCT (Discrete Cosine Transform), the
electronic watermark information may be embedded in a particular
DCT factor, for example, a DC factor.
[0120] This arrangement allows, also in the case of compressed
digital data, the detection of the completion of copy by detecting
the start and end positions of information content by use of
electronic watermark information.
[0121] In the above-mentioned embodiment, for content ID and copy
control information, PN codes of different series are used. It will
be apparent that, for the PN codes of different series, portions
having different phases generated by the PN code generating block
of the same PN series may be used.
[0122] It is also practicable, as shown in FIG. 9, to alternate
8-bit copy control information and 8-bit content ID, which are
spectrum-spread by one PN code to be superimposed on the
information content.
[0123] Referring to FIG. 10, there is shown an exemplary
configuration of the WM forming block 3 to implement the
arrangement shown in FIG. 9. As shown, a content ID from the
content ID generating block 4 and copy control information from the
copy control information generating block 5 are supplied to a
synthesizing block 306 to be combined in alternation of 8-bit basis
as shown in FIG. 9.
[0124] The content ID and the copy control information combined in
the synthesizing block 306 are supplied to a spreading block 307 to
be multiplied by a PN code series supplied from a PN generating
block 308 for spectrum-spreading. Then, a resultant spread-spectrum
signal supplied from the spreading block 307 is supplied to the WM
superimposing block 2 to be superimposed on the information
content.
[0125] In the above-mentioned example, use of a single PN code
series alone can superimpose content ID and copy control
information including start and end flags onto information content
as electronic watermark information and detect it from this
information content.
[0126] Another Embodiment of the Method of Detecting Start and End
of Information Content:
[0127] In the above-mentioned embodiments, the start and end flags
are superimposed on information content as electronic watermark
information and the beginning and end of the information content
are detected by detecting these start and end flags, detecting the
completion of copying. However, the completion of copy may be
recognized without superimposing the start and end flags. Namely,
the completion of copy may be detected by detecting the content IDs
repeatedly superimposed as electronic watermark information from
the beginning to the end of information content as shown in FIG. 4
and then detecting the change points of these content IDs.
[0128] To be more specific, a content ID is unique to each piece of
information content and therefore different pieces of information
content have different content IDs. Therefore, detection of the
difference between content IDs can detect the start and end points
of time of each piece of information content, namely the separation
between pieces of information content.
[0129] Referring to FIG. 11, there is shown a flowchart for
describing the copy control processing in the above-mentioned case.
This flowchart differs from the flowchart shown in FIG. 8 in the
method of detecting the start and end points of time of information
content.
[0130] Namely, in the example shown in FIG. 11, when, after start
of a copy recording operation in step S3 like the example shown in
FIG. 8, ISRC, which is the content ID superimposed as electronic
watermark information, is detected from the soundless portion (step
S21), the controller 40 determines the beginning of that
information content (step S22). Then, the controller 40 uses the
detected ISRC to search the copy history information managing
memory 41 to determine whether the past history of that information
content is stored in the table TB in the memory 41. (step S23).
[0131] If the past history is found in the table TB, the controller
40 checks the copy permitted count for that information content
(step S24). If the count is 0, the controller 40 stops the
recording operation (step S8). If the count is 1 or more, the
controller continues the recording operation and further detects
the ISRC of the content ID attached to the information content to
determine whether the ISRC has changed (step S25). Then, when a
change of the ISRC has been detected, the controller 40 determines
the completion of copying. When copying is ended by the key
operation by the user, the controller 40 decrements the copy
permitted count of the copied information content by one in the
table TB in the copy history information managing memory 41,
updating the copy history information (step S10).
[0132] If the past history is not found in the table TB in step S6,
the controller 40 sets the content ID namely ISRC in the copy
control information attached to that information content and the
copy permitted count to the table TB as a preparatory operation for
storing a record in the copy history information managing memory 41
as the information content entered in the recording apparatus for
the first time.
[0133] Then, the controller 40 continues the recording operation to
further detect the ISRC of the content ID attached to the
information content. When a change of the ISRC has been detected,
the controller 40 determines the completion of copying. When
copying is ended by the key operation by the user, the controller
40 decrements the copy permitted count for the copied information
content by one in the table TB in the copy history information
managing memory 41, updating the copy history information (step
S10).
[0134] In the present embodiment, effective use of the content ID
superimposed on information content as electronic watermark
information can detect the completion of copying of the information
content.
[0135] It should be noted that, in the above description, the start
point of time of information content is detected as the point of
time at which ISRC has been detected from the soundless portion.
However, this applies only to the first piece of information
content. When copying two or more pieces of information content
consecutively, an ISRC change point is detected as the end point of
the preceding information content and the start point of the
current information content.
[0136] In the above-mentioned two embodiments, CGMS information as
copy generation control information is recorded along with copy
control information. Only managing copy permitted count can perform
copy control, so that CGMS information need not be
superimposed.
[0137] In the above-mentioned embodiments, copy permitted count
information is included in copy control information. If the copy
permitted count in the recording apparatus uses a method in which a
predetermined certain count provides a limit, the content ID of the
information content entered for the first time and the
predetermined limit (maximum) of the copy permitted count are set
to the table TB, thereby initializing the copy history. Therefore,
the copy permitted count information may not be included in the
copy control information to be superimposed on the information
content.
[0138] In the case of digital information, CGMS information may be
attached not as electronic watermark information. This holds with
the copy permitted count information.
[0139] In the case of information content in the form of an analog
signal, the entire copy control information must be superimposed as
electronic watermark information. In the case of a digital
compressed signal, the copy control information may be attached to
an area separate from the data area. In this case, however, the
start and end flags are superimposed as electronic watermark
information for an analog signal or a baseband digital signal.
[0140] The information content to which the present invention is
applied is not only audio information content but also video
information content for example.
[0141] In the above-mentioned embodiments, the start and end flags
are used for the detection of the completion of copying when
controlling copying of information content provided in a recording
medium. The present invention is also applicable to examples in
which information content is provided as broadcast signals or
through the Internet.
[0142] After the completion of copy, the copy history of the
recording apparatus is updated as post-processing in the
above-mentioned embodiments. This invention is also applicable to
an example in which billing is executed as post-processing after
the information content provided through the Internet has all been
downloaded and stored in the memory (namely duplicated).
[0143] It will be apparent that the electronic watermark processing
is not limited to the above-mentioned spread spectrum
processing.
[0144] As described and according to the invention, the completion
of copying can be surely detected for each piece of information
content. Consequently, if copy fails due to an operation error made
by user for example, the failed copy can be invalidated for user
advantage.
[0145] The information for detecting the start and end of
information content is superimposed thereon as electronic watermark
information. Consequently, it is difficult to tamper this start and
end of the information for detecting information for unauthorized
copy of the information content. Therefore, the present invention
provides reliable copy control management.
[0146] While the preferred embodiments of the present invention
have been described using specific terms, such description is for
illustrative purposes only, and it is to be understood that changes
and variations may be made without departing from the spirit or
scope of the appended claims.
* * * * *